Various electronic equipment or devices can communicate using wireless links. A popular technology for communication with low-power portable devices is radio frequency identification (RFID). Standardized RFID technology provides communication between an interrogator (or “reader”) and a “tag” (or “transponder”), a portable device that transmits an information code or other information to the reader. Tags are generally much lower-cost than readers. RFID standards exist for different frequency bands, e.g., 125 kHz (LF, inductive or magnetic-field coupling in the near field), 13.56 MHz (HF, inductive coupling), 433 MHz, 860-960 MHz (UHF, e.g., 915 MHz, RF coupling beyond the near field), 2.4 GHz, or 5.8 GHz. Tags can use inductive, capacitive, or RF coupling (e.g., backscatter, discussed below) to communicate with readers. Although the term “reader” is commonly used to describe interrogators, “readers” (i.e., interrogators) can also write data to tags and issue commands to tags. For example, a reader can issue a “kill command” to cause a tag to render itself permanently inoperative.
Radio frequency identification systems are typically categorized as either “active” or “passive.” In an active RFID system, tags are powered by an internal battery, and data written into active tags can be rewritten and modified. In a passive RFID system, tags operate without an internal power source, instead being powered by received RF energy from the reader. “Semi-active” or “semi-passive” tags use batteries for internal power, but use power from the reader to transmit data. Passive tags are typically programmed with a unique set of data that cannot be modified. A typical passive RFID system includes a reader and a plurality of passive tags. The tags respond with stored information to coded RF signals that are typically sent from the reader. Further details of RFID systems are given in commonly-assigned U.S. Pat. No. 7,969,286 to Adelbert, and in U.S. Pat. No. 6,725,014 to Voegele, both of which are incorporated herein by reference.
In a commercial or industrial setting, tags can be used to identify containers of products used in various processes. A container with a tag affixed thereto is referred to herein as a “tagged container.” Tags on containers can carry information about the type of products in those containers and the source of those products. For example, as described in the GS1 EPC Tag Data Standard ver. 1.6, ratified Sep. 9, 2011, incorporated herein by reference, a tag can carry a “Serialized Global Trade Item Number” (SGTIN). Each SGTIN uniquely identifies a particular instance of a trade item, such as a specific manufactured item. For example, a manufacturer of cast-iron skillets can have, as a “product” (in GS1 terms) a 10″ skillet. Each 10″ skillet manufactured has the same UPC code, called a “Global Trade Item Number” (GTIN). Each 10″ skillet the manufacturer produces is an “instance” of the product, in GS1 terms, and has a unique Serialized GIN (SGTIN). The SGTIN identifies the company that makes the product and the product itself (together, the GTIN), and the serial number of the instance. Each box in which a 10″ skillet is packed can have affixed thereto an RFID tag bearing the SGTIN of the particular skillet packed in that box. SGTINs and related identifiers, carried on RFID tags, can permit verifying that the correct products are used at various points in a process.
In industrial and commercial processes, raw materials are matched to the specific machines that process them. For example, in inkjet printing presses, it is necessary to provide the correct color of ink to each printhead. It is further necessary to do so while permitting different sizes and shapes of ink containers to be used, depending on the needs of each customer. JP2010-023322 describes surrounding inter-antenna spaces with magnetic material to reduce mutual interference between adjacent RFID tags on interchangeable units of an image-forming apparatus. However, this magnetic material restricts the size and shape of interchangeable units that can be used. U.S. Pat. No. 7,106,196 describes fine-tuning read range of RFID devices. However, this scheme requires a surface treatment deposited on an RFID device.
Examples of inkjet printer ink supply systems are given in U.S. Pat. No. 7,401,052, which is incorporated herein by reference.
There is, therefore, a continuing need for ways of reliably, flexibly using RFID technology to reliably fluids to be supplied to a machine.